Mustafa Ozsipahi, Sertac Cadirci, Hasan Gunes, Husnu Kerpicci, Kemal Sarioglu

Abstract

The aim of this study is to numerically investigate theeffects of various parameters on the lubricant (oil)-coolant two phaseflow in the lubrication system of hermetic compressors commonlyused on household refrigerators. Lubrication oil is pumped from thesump through an asymmetrically opened hole on the bottom of thecrankshaft (suction side or inlet) by its rotational motion and climbsas an oil film on the internal surface of the helical channel carved onthe crankshaft surface. This oil film is directed to crankshaft upperexit discharging into the coolant refrigerant and it is used tolubricate the moving components of the compressor including thecylinder piston. The oil forms an immiscible mixture with coolant,thus a two phase flow model using Volume of Fluid (VOF) method isused. Specifically, the mass flow-rate of oil is determined as afunction of the rotational speed, oil viscosity and the submersiondepth of the crankshaft in the oil-sump. With increasing rotationalspeed and submersion depth, the mass flow-rate through thecrankshaft upper exit also increases. With increasing oil viscosity themass flow-rate through the crankshaft upper exit decreases due to theincreased friction.